Traffic control



J. c. BUERKE TRAFF I C CONTROL June l, 1937.

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.TRAFFI CONTROL v Filed Sept. 15, 1928 5 Sheets-Sheet 3 lJune l, 1937. J. c. BUERKE Y TRAFFIC CONTROL Filed sept. 15, 192e 5 Sheets-Sheet 4 o G w W was am uw sm EQW G0 June 1, 1937". J C BUERKE 2,082,479

TRAFFI C CONTROL Filed Sept. 15, 1928 5 Sheets-Sheet 5 annuncia@ Patented June l, 1937 UNITED vSTATES TRAFFIC CONTROL Jesse C. Buerke, Tampa, Fla.; Elsie A. Buerke administratrix of said Jesse C. Buerke, de-

ceased Application September 15, 1928, Serial No. 306,119

22 Claims.

The invention relates to traiiic control methods and systems for cities and towns.

In general, two types of such systems have .gone into use. One such system yis known as the synchronous system in which all north-south traiic throughout the area under common control will move at the same time while all east-west traffic is stopped and the reverse. An advantage of this system is that where trailic in one direction preponderates, this trafhc may be given a greater proportion of moving time than that given the traffic of lesser volume.

The second system in use is that known as the progressive system in which the go lights in each street are alternated with the stop lights at consecutive intersections in such a man' ner that a vehicle driven at the proper speed may proceed the full length of a street without being halted by a signal turned against it. A disadvantage of the latter system has been that it has vbeen necessary, so far as known to me, to operate the signals in the two directions on a fiftyfty time proportion basis. That it is impossible to vary proportions from a fifty-fifty basis in a simple, alternated-color, progressive signal system is evident when considering that the signals in any direction of travel are of opposite color at the same instant at consecutive intersections, and if the larger portion of the time cycle is given 30 to one direction of travel at one intersection, the cross travel at the next intersection is receiving the same large portion, `and the through trafc will receive the remaining small portion of the cycle at the said next intersection.

Unlike the methods which attempt to oiiset this iniiexibility of the progressive system by progressing waves of `traiiic in one general direction at the expense of the directly opposite trafc, (with more or less complicated means for generally reversing the progression), by adjusting the lag of the individual intersection control means in its cycle in conformity with the distance between successive signal stations, the traffic moving at a iixed speed in one direction, as exemplified in patent to Woodford, 1,659,904, Feb. 21, 1928, the present system maintains a iixed angle of like signals in the signal cycle between all signal stations to give equal consideration t'o traiiic in directly opposite directions, and varies the speed of traffic in accordance with the lengths of the individual blocks, with compensating means for extra long or extra short blocks, and provides, selectively at any intersection, any desired proportion of go time between through and vcross traiic at that intersection, and moves all traic trains continuously in strict coordination by maintenance of defini-te relations between the mid-points of all trains. Bythe term train is meant the' space or area, moving through a street system in accordance with lthe progression of signals, within which vehicles may pass the intersections of the street system without being stopped by the signals, whether said space or area actually contains traffic or not..

It is an object of the present invention to combine the advantages of the synchronous and of the progressive systems and to provide an unlimitedly exible progressive system, wherein a vehicle may proceed uninterruptedly in either direction, north-south or east-west, yet the direction of preponderating trafc may be given a major proportion of the moving time.

It is a further object of the invention to provide for a variation of the proportion of moving time allotted to through and cross traiiic at individual street intersections.

It is a further object of the invention to provide means wherein individual street intersections may have the moving time equally divided between the two directions while other intersections in the same system may have various proportions allotted to the two directions.

It is a further object of the invention to provide a system in which a major proportion of moving time may be allotted to trafc moving in one direction in one portion of an area and a minor proportion may be allotted to the same direction in another portion of the same area. It is a further object` of the invention to provide a system in which a continuously moving trac train may be varied in length during its progress to agree with the amount of traffic.

It is a further object of the invention to provide a system which may be started into operation by displaying, at each intersection, first a caution signal followed by a go" signal for its full normal period which will serve to initiate immediately the movement of traic trains of full normal length, to reduce confusion at `starting, and which may also be cut out of action at each intersection at the end of a f'u-ll normal` period of signal display to insure the passage of ent-ire trains past intersections before allowing interference of uncontrolled traflic.

It is a further object of the invention to provide signals, which it is preferred to designate as phantom signals, in long blocks at points 'at which intersections would occur if intermediate perpendicular short streets were cut through, and in other intermediate points, Asuch as lon diagonal streets between intersections, and elsewhere in order to keep traic in step and to serve as an index to the proper speed along such blocks to enable such traiic to arrive at the end of such blocks at the correct time for continuous movement.

It is a further object of the invention to provide a system having means for the division of the moving time into three or more parts at intersections of more than two streets, and at normal crossings Where a special left turn period is desired.

It is a further object of the invention to provide a system for controlling trac through diagonal streets cutting across rectangular blocks so as to secure the progressive movement of trailic on all of said streets.

It is a further object of the invention to provide a system having provision for controlling traffic during a fire to group traii'ic in selected areas and provide a relatively clear path for re apparatus past held traffic.

It is a further object of the invention to provide means controllable from a re engine house to group tralic in selected areas and provide a relatively clear path through a definite run of the iire apparatus.

It is a further object of the invention to provide a system in which individual signal stations may be taken over by an olicer for manual control without interfering with the automatic control of the remainder of the system even though the central control apparatus be out of action.

It is a further object of the invention to provide for the manual locking of individual signals in a fixed position to provide for the continuous display of a stop signal for one direction at an individual intersection without interfering with the normal operation of the caution and go signals for the cross direction at that intersection, in order to provide for blocking off a single street or an area for such occasions as parades or res.

It is a further object of the invention to provide a system in which go signals bear an indication of the necessary speed to permit of continuous movement of the vehicle past the next intersection.

It is a further object of the invention to provide an unlimitedly flexible progressive system in which a dual common timer is provided so constructed that, for a given direction, the mid-point of the time of the go signals of each portion is substantially synchronized with the mid-point of the time of the stop signals of the other portion.

It is a further object of the invention to provide a system as stated in which are utilized a plurality of dual timers giving different proportions of times to go and stop signals with provision to connect any individual signal to the timer giving the desired proportions of the time cycle.

It is a further object of the invention to provide a system that may be operated by a small number of wires carried successively to the signal stations.

It is a further object of the invention to provide a system to which electrical energy may be added at various points to carry the load and to reduce the wire sizes required.

It is a further object of the invention to provide a system in which certain or all of the signals may be operated through more than one path for the electric energy.

Further objects of the invention will appear from the foiiowing description when read. in connection with the accompanying drawings showing illustrative embodiments of the invention, and wherein:-

Fig. 1 is a diagrammatic view showing one relative time relation of various signals in the system to each other;

Figs. 2 to 9 inclusive are diagrams of streets indicating schemes of signals and movement of trafiic therealong and past intersections thereof in the single time relation shown in Fig. 1;

Fig. l0 is a diagram of streets showing certain streets not cut through resulting in a long block on other streets;

Fig. 11 is a diagram of streets where one street cuts across a network of other intersecting streets;

Fig. 12 is a diagram of circuits at a central control station;

Fig. 13 is a diagram of circuits at a street intersection;

Fig. 14 is a diagram of circuits for re control of traflic through a selected route only;

Fig. 15 is a diagram of circuits at a street intersection such as shown in Fig. ll where three streets intersect.

In accordance with the invention the signals at the intersections of a network of intersecting streets are connected alternately into two series of signals, the signals at certain of the intersections being indicated by a rectangle which will be referred to as A signals and at alternate intersections the signals are indicated by diamonds and will be referred to as B signals.

In the scheme of illustration adopted in Figs. 2 to l0 inclusive, the diamond or rectangle when turned with its longest dimension coinciding with the axis oi a street indicates that at that time the signal is set for go at that street and when turned with their longest axis across the street indicates that they are set for stop at that time upon that street.

Caution periods are indicated by placing the diamond or rectangle at an angle to the axis of both streets.

In Fig. 1 the dot and dash lines cutting across the time-interval-showing belts upon the diagram L indicate the nature of the signal upon A and B circuits at the moment illustrated by the gure whose number appears above the dotted line. Thus dot and dash line 2 will indicate the con dition of the signals in Fig. 2 at the moment of time they are illustrated. As shown, the east-west intersections, carrying A signals, have just entered upon the go period of time as indicated by belt 20, which reads from left to right in Fig. l

beginning with the dot and dash line 2, and

the B signals are at an intermediate point of their go period upon east and west streets as indicated by the belt 2 I. The broken line at the right hand end of belt 2| in Fig. l, and at the left hand end of the same belt in this figure, indicates that the time interval indicated by belt 2| is continuous from the right hand end of the gure up to the dot and dash line 3 of Fig. 1.

The illustrations of Figs. l to 9 inclusive are chosen to illustrate a preponderance of eastwest traffic and where in accordance with such preponderance the east-west trac is given substantially '75% of the moving time at each intersection and the north-south traic is given 25% of time, one-half of the caution periods being deducted from each of the percentages. The traffic trains which result from the operation of the signals are indicated in these gures diagrammatically by arrows. The direction of movement is indicated by the direction in which the arrow is pointed for each train, and the relative lengths of the trains are indicated in the central portion of the gures by the relative lengths of the arrows. The position of the front ends of trains entering the figures is indicated by the points of the arrows, but such trains are broken away at the boundaries of the iigures. To avoid confusion, the area within the gures is illustrated in Fig. 2 as clear of traic trains, except for the trains beginning to enter the boundaries. 'Ihe gures in their numerical order illustrate the progress of only these trains, with others which subsequently enter the area. As previously stated, the term traidc train refers not to actual moving vehicles, but to the space within which a moving vehicle may pass street intersections in accordance with the progression of the traffic signals Without stop.

At the moment when the A signal upon D Street at lst Street, Fig. 2, is turned to go, a traino train indicated by an arrow 23 has just reached said intersection and the B signal upon D Street at 2d Street is also still set for go as indicated by the belt 2l, no recent change having been made in the B signal at 2d Street.

Diuing the interval of time between Fig. 2 and Fig. 3, the trailc train 23 has crossed the intersection of 1st and D Streets to the position shown in Fig. 3 and a traiic train 241s just approaching D Street on 2d Street.

At the instant indicated by Fig. 3l and by dot and dash line 3 on Fig. l, the B signal at 2d and D Streets is turned to caution, trahie train 24 being at this instant approaching the caution signal. Also a traic train traveling west on D Street has reached a position across 3d Street corresponding to the position of train 23 travelling east across 1st Street.

In Fig. 4, which corresponds to dot and dash line 4 on Fig. l, the caution period at 2d and D Streets has ended and the traffic train 24 has the go sign upon 2d Street, the trains 23, 25 being still in motion approaching said intersection.

In Fig. 5 the short traino train 24 has passed the intersection of 2d and D Streets, the signal at which crossing has changed to caution, and the heads of trains 23 and 25 have almost reached said intersection, having a distance to travel which will be covered during the caution period at 2d and D Streets.

At the instant of time shown in Fig. 6, the B signal at 2d and D Streets has turned to go whereby it has been unnecessary for the traiiic trains 2s and 25 to stop and traflic train Zllhas passed this intersection and is still in motion toward the intersection of 2d and E Streets.

It will be noted that from the beginning of the interval shown in Fig. 2, the A signals at 1st and D Streets and at 3d and D Streets have been continuously turned to permit movement along D Street.

In Fig. 7 traic train 23 has entirely passed the A signal at 1st and D and traic train 25 has entirely passed the A signal at 3d and D, which signals have turned to caution and are being approached by north-south bound traflic trains which will not be stopped as these signals are about to show north-south go as indicated in Fig. 8 and in Fig. 8 traic trains 23 and 25 are still proceeding across 2d and D Streets.

Fig. 9 shows traffic trains 23 and 25 still proceeding across 2d and D Streets, their heads having reached a position at the caution distance from 3d and D Streets and 1st and D Streets respectively, which corresponds to the interval immediately preceding that shown .by Fig. 2, the caution position of the A signals being the caution position which immediately precedes the A go period shown in Fig. 2.

It will thus be seen that both north-south and east-west bound traiic are allowed to proceed continuously along their respective streets. The interval periods 2l.) and 2l for go east-west and stop north-south upon the A and B signals respectively are of the Same length. So also are the time belt 26 for A signal go north-south and stop east-west and the time belt 21 for B signals go north-south and stop eastwest. Also the caution period belts 28, 29,' 3Q, and 3l are of equal length throughout.

It will also be seen that the central point of belt 2'1 which indicates go north-south upon the B signals coincides with the central point of belt 2l) which indicates go east-west on the A signals, the overlapping ofr the go periods in these two directions being permissible because of the alternate relation of the A and the B signals upon each street. Similarly the central point of the belt 26 indicating go north-south upon the A signals coincides with the central point of the go east-west of the B signals as indicated by belt 2l, and in each case go eastwest or north-south corresponds to stop northsouth or east-west respectively.

The foregoing description in connection with Figs. 1 to 9 inclusive is simply for the purpose of illustrating how a simple dual interlaced signal system progresses traino continuously in all directions over a network of streets in accordance with traic demands which preponderate uniformly in one direction over the cross direction. By using two of any of the standard variable timers nowcommonly used with the socalled synchronous systems for the two phases A and B of Fig. l, and maintaining the required phase angle between the two, a system of progressive control may be made variable at will for one general direction uniformly as against the cross direction.

Since trafiic conditions and demands are continually varying from intersection to intersection, and at the same intersection at different hours. it is desirable that a system be made unlimitedly flexible in order to meet these demands.

To accommodate these irregularities,` this .in-

vention provides a plurality of suitable, xedproportion, dual interlaced systems, having a common drive, with the mid-point of correspending signal displays in each system having like angular position in the cycle, each of the plurality of systems being made available selectively at each intersection for use by the signal control stations, as may be desired at the individual intersections.

As the mid-point of a signal display corresponds to the mid-point of the resulting train or of the clear space between trains, the maintenance of proper relation between all of the midpoints of all the systems insures a corresponding position of the train and void center points of all the systems. Varying the proportion of the cycle time devoted to go and stop signal periods While maintaining common midpoints, results in either an earlier or a later display of the given signal by an equal amount at the beginning and ending of the period, and the train or void length will be lengthened or shortened equally at front and rear ends.

By the selection of the control means at any signal station giving the relative proportion of time to through and cross traiiic needed at that intersection, each signal station along a given street may be using a diierent tim-e proportion for its signals from the proportions used at either the preceding or the succeeding signal station, and the traffic trains controlled by these stations may be progressing at a uniform speed while varying in length at each intersection. As noted later, the speed of the trains will also be Varied to agree with variation in length of blocks, and the coordinated signals will cause the arrival of the mid-point of each train moving in one direction at any intersection to be coincident with the arrival of the mid-point of trains moving in the cross direction at adjacent intersections.

It will be evident that as a train progresses 1n continuous movement along a street, when it reaches a section in which traffic becomes heavy because of influx of vehicles, the train should be lengthened; and when it passes into a section where traffic is lighter because some of the vehicles have left the street, the train may be shortened for the benefit of cross traffic.

For continuous movement in an alternated color signal system, the time cycle of lights must be of such duration that the change to a go signal will come at exactly the instant a car traveling at the prescribed speed from the beginning of a signal block arrives at the beginning of the next. Lengthening the time cycle simply demands that the traiic move slower if it would progress without stop, and conversely, shortening the time cycle requires that the traffic move faster to keep from being trapped within the block by the stop signal.

In the development of any progressive system, there are two dependent variables, the time cycle and the rate of speed, since the block length is fixed in any city. The time cycle has practical limitations. If it is made too long, traffic will be slowed too much and it cannot be shorter than the time required for a pedestrian to cross the street safely (in the absence of safety islands). With the block length fixed, the traiiic train speed varies inversely with the length of the time cycle. To increase the trafc speed, the time cycle should be as short as is practical.

Cross trac is a problem connected only with the use of the common crossing area and is provided for in this system by dividing the cycle into proportions of go signals suited to the demands of cross and through traic. The amount of cross trafc has nothing to do with the length of the time cycle.

In the illustrated final form of this plurality of two-phase dual interlaced systems, a number of economies have been effected in central office apparatus and feed lines by the use of interlocking and reversing features, whereby certain parts are made to serve for more than one purpose, thus reducing the number of wires, timers, etc.

However, throughout the evolution, the essential maintenance o'f a phase angle of 180 in the total time cycle has been preserved between the central time point of a given signal for a given direction at one signal station and the same point of like signal at the next succeeding normal' intersection signal station. This accomplishes a comparable signaling relation between the "A and B stations to that illustrated in the simple form of Fig. 1, and as though the dual interlaced circuits were actually provided upon a plural basis with each circuit connected to alternate signal stations, even though these signal stations are not at street intersections.

To bridge the transition through several steps in the evolution of this system, the following explanation will show the relation of the features and their functions. Relays operating on the electric balance principle are provided at the intersection signal stations, as shown in Fig. 13, for actual control of the signal lamps. The relays at intersections corresponding to the rectangular symbol locations in Figs. 2 to 9 form an A group of control stations and the relays at the diamond symbol locations form a B group of control stations. The outside legs of all relay balances are permanently connected to the outside potential lines 31 and 41. The middle points of these relays are supplied with various relative potentials to the lines 31 and 41, through five control lines from a central oiiice mechanism and autotransformer taps shown in Fig. 12, any one of the ve lines being capable of selection at will at any station. Each of the ve signal station control lines originates in a contact arm operated by cams 32, 33, and 34 to give three different potential connections from transformer H9, (Fig. 12), the terminal ends of which connect across potential lines 31 and 41.

Each of these potential connections operates to bring all of the signal station relays which happen to be selectively connected to the line to which it is applied to a corresponding definite position of their contact arms |30, (Fig. 13). The center contact and potential of these three operates to give a caution signal.

V It will be noted that there is a phase angle of 180 of the cam cycle between the arms actuated b v cams 32 and 33, whose peripheries are so divided into segments of different radii that they give unequal proportions of their cycle to two of the operating potentials. Cam 34 operates only one arm and control line since it gives equal proportions of cycle time to each of the two mainv operating potentials.

Cams 32, 33, and 34 are fixed upon their common driving shaft in such position that the central points of the segments having the longest radius line up, as do also the central points of r the cam segments having the shortest radius. This synchronizes the mid-time point of each of the two resulting potentials on each of the lines feeding from contact arms of like angular position in the cam cycle, as arms H6, |60, and |54, and wires H4, 22|, and 224; also arms |58 and IGI, and wires 233 and 23| respectively.

At the intersection signal stations, these applications of given potentials for definite periods With fixed angular relations in the time cycle are translated into the desired traflic signals of the proper duration and phase values as described later in detail.

For control of the signals in the system, there is illustrated in Fig. 12 a series of circuit closers 32, 33, and 34, circuit closer 32 being designed to give signals for one direction of traic of the go time while for the cross direction signals are being given 25% of the go time or vice versa. Circuit closer 33 is designed to give the respective signals a proportion of 60% to 40% and circuit closer 34 is designed to give each go signal one-half of the total moving time.

The remainder of the illustration of Fig. 12 shows diagrammatically the circuits and appainclusive.

ratus for starting the system into operation, for stopping the operation of the system, and for manipulating the signals in case of fire.

For purposes of illustration in connection with Figs. 2 to 9 inclusive, the A and B signals in said figures are assumed to be placed under control of circuit closer 32 and to be properly connected to give the east-west traino 75% and the northsouth trafc 25% of the moving time, the A signals receiving their control through cam contact arm ||6 and the B signals receiving their control through cam contact arm |58, these arms being spaced diametrically opposite each other in contact with the rotating cam member of the circuit closer 32 so that the phase angle between them is substantially 180 of the cycle. The rotary cam elements of the circuit closers 32, 33, and 34, with the commutator drum 82, are secured on a common shaft driven at a fixed speed by the motor 35.

When it is desired to start the system into operation, the motor 35 and the cam shaft having rst been set into motion, a circuit closer 36 will be momentarily operated closing a circuit from power line 31 through wire 38, wire 39, normally closed contacts 40, wire 4|, contacts 42, wire 43, solenoid 44, wires 45, 46 to the opposite power line 41. The power lines 31, 41 are shown as continued through a cable of a plurality of conductors to a signal control box shown at the right of Fig. 13.

By the circuit just traced solenoid 44 will be energized by which means contacts 48, 49 and 50 will be closed and contacts 5| and 52 will be opened, contacts 5I and 52 being interlocking control contacts for the re and stop controlling circuits respectively.

Byclosing contact 48 a holding circuit will be closed through solenoid 44 from wire 41 through 46, 45, solenoid 44, contacts 48, wire 53, which is a bus wire, connecting with each of contacts 54, 55, 56, 51, and 58 by means of wires 59, 60, 6|, 62, and 63. The last named contacts are in contact with the lower portion of heads t4, se, as. ci, and sa from which heads the holding circuit will be closed through wiresA 69-13 inclusive and by bus wire 14, to the other side of the circuit at wire 31. The arms or walking beams 11-8I inclusive will remain inrtheir central position until the commutator drum 82 has turned to bring one of the segments thereon into contact with two of the Abrushes B4, one of each pair of brushes 84 being -connected respectively to one of each of pairs of solenoids 85-94 The commutator drum 82 with its connections forms a delayed-action mechanism for the sequential starting and stopping of the system and for the sequential stopping of traiic in preparation for movement of fire apparatus, as described later.

The commutator drum 82 is mounted on the same shaft with the rotary cam elements of the circuit closers 32, 33, and 34, and the contact segments of the commutator drum each correspends to one of the caution periods produced by revolution of the circuit closer cams.

As each caution period segment on the commutator drum comes into its rst contact with a pair of brushes 84, after the pushing of the starting button, a circuit will be closed through one of the solenoids 85, 81, 89, 9| and 93.

In the initiation of the circuit through the A signal shown in Fig. 13 as corresponding to the signal atv 1st and D Streets, Fig. 2, theactuating circuit for the solenoid 85 will be `as follows: line 31, wire 16, contacts 50, wire 95, Wire 15, wire 96, brush 91, continuous band 98 of the drum, segments 99, brush |00, wire wire |02, solenoid 85, wires |03, |04, contacts 49, wire 46 to the other side 41 of the line.

Continued revolution of drum 82 will result in closing the like circuit through each of solenoids 81, 89, 9|, and 93 to cause the walking beams 18-8i inclusive to be tipped downwardly at their left ends when the first caution period arrives in connection with each of the arms of the circuit closers 32, 33, and 34. The depression of the walking beams 11-8| inclusive will result in breaking the contact between the heads 64-68 inclusive and the contacts 54-58 inclusive whereby the solenoid 44 will be released and the control apparatus at the bottom of Fig. 12 will be returned to the position shown in full lines in the drawings, but the Walking beams, by such means as indicated at. |05, comprising a gravity member seating in recesses |06, |01, or |08 will retain the walking beams in the position to which they are brought by action of the solenoids. In this position of the walking beams switches |09||3 inclusive will be thrown upwardly and in the circuit to the signal control shown in Fig. 13 will connect wire ||4 with wire H which leads to the signal control.

At the caution period under consideration, the arm 6 of circuit closer 32 will be in contact with ||1 thus providing a pathA for current from the potential point ||8 of vautotransformer ||9 through wire |20, contact ||1., arm ||6, wire ||4, contact |2l, wire ||5, socket |22, through a plug |23 inserted therein, wire |24 to solenoids |25, |26; from solenoid |25 through wire |121 to line 31, and from solenoid |26, Wire |28 to line 41, which lines 31 and 41 are continuous throughy the cable from the central station.

Sincethe point I8 is connected to transformer ||9 at a point nearer 31 there will be a greater difference of potential for current passing through solenoid |26 than through solenoid |25 which will cause the walking beam |29 to assume an intermediate position bringing .its arm |30 upon "caution contact |3I, thus providing a path for current through all the caution lights at the corner of 1st and D Streets by thefollowing path: wire 31, the caution lights |32, wire |33, |34, contact |3I, arm |30 towire 41, thus displaying the caution signals.

Upon continued revolution of circuit closer 32, the arm l I6 will be brought into contact with |35 thus providing a path for current from wire 31 past the end of transformer I|9 through wire |36, contact |35, arm ||='6, wire ||4, contact |2|,` wire ||5,' socket |22, plug |23, wire |24, to solenoids |25, |26, and thus to wire |21. `Since the' solenoid 26 will then receive the entire difference of potential between wires 31 and 41, and solenoid |25 will receive none of the difference of potential, being substantially short circuited, the walking beam |29 will be moved to the exterior position shown in Fig. 13, thus closing a path for current through east-west go lamps |31, wire |38, normally closed switch |39, wire |40, reversing switch |4|, wire |42, go contact |43, afm lsu, to wire 41, thus dispiaymg the gew signals for east-west trafiic at 1st and D Streets. There will also be closed a circuit through northsouth stop lights |44 at said intersection through wire |45, switch arm |46, wire |41, reverslng switch |48, Wire |49, Contact |50, arm

' lng beam arms 11, 18, 19, 80, 8|, respectively, are

|30, to wire 41, thus displaying the stop lights at said intersection.

Continued revolution of circuit closer 32 will cause arm ||6 to contact with |5| thus closing a circuit from wire 31 to wire 41 through the solenoids |25, |26 at the intersection control apparatus as follows: wire 31 and wire 41 or transformer potential H9, at point |52 thereof, wire |53, contact |5|, arm H6, wire ||4, contact |2|, wire H5, socket |22, plug |23, wire |24, the solenoids, and thus tol wires 31 and 41.

In this position of arm H6, which in passing thereinto has contacted with "caution contact ||1 thus again closing arm |30 with contact |3|, the greater portion of potential between wires 31 and 41 will be impressed upon solenoid |25 and the lesser portion upon solenoid |26, thus tipping the walking beam to an intermediate reversed position from that shown in Fig. 13 wherein arm |30 will connect with contacts |54, |55, thus closing circuits through north-south go lamps |56 and east-west stop lights |51.

Continued revolution of circuit closer 32 will repeat the cycle already described so long as the Walking beam 11 remains in its tilted position described.

The circuits traced are common to all A signals which are given a ratio of '15% go eastwest and 25% go north-south of the total cycle. The opposite arm of circuit closer 32 will likewise control all B signals allotted a like proportion of time in the case of which signals the arm |58 will control the circuits at the central station through contact |59. Likewise the arm |60 of circuit closer 33 will control A signals given a proportion of 60% to 40% and the arm |6| will control B signals given a proportion of 60% to 40% of the moving time, the latter arms working through contacts |62 and |63 respectively.

All A and B signals will be controlled in common by arm |64 of circuit closer 34 through contact |65, the red and green lights in one direction being closed by one of the outside contacts of circuit closer 34 and the green and red lights of other switches being controlled by the other outside contact of said circuit closer, the central contact controlling all of the caution signals at intersections which will give a 50%-50% ratio.

When it is desired tostop the system, the action is likewise brought about at a caution period at each signal station and is accomplished by closing circuit closer |65', thus providing a path for current from wire 31, the circuit closer wire |66, contacts 5|, wire |61, contacts |68, wire |69, solenoid |10, wires |1|, |12, to wire 41, thus closing a holding circuit to solenoid |10 via wire 41, wires |12, |1|, contacts |13, closed by energization of the solenoid, wire |14, bus wire |15, wires |16|80 inclusive, heads 64 to 68 inclusive, wires 69-13 inclusive, bus wire 14 to wire 31.

The solenoid |10 will thus remain energized until current has been passed through each of solenoids -94 inclusive by the path as follows wire 31, wire |8|, contact |82, wire |83, wire 15, wire 96, brush 91, continuous band 08 of drum 82, a caution segment upon the drum 82, through alternate brushes 84, solenoids 86-88- 90-92-04, wire |84, wire |65, contact |86, and wire |12 toI 41, and also through the other alternate brushes 84, solenoids 85-81-89-9I-93, wire |03, wire |04, Contact |86', and wire |12 to 41.

As solenoids 85--86, 81--88, 89-90, 9|92, 93-94 being paired on opposite ends of the walkenergized in pairs with full and equal potential through the commutator 82, they will, due to the position of their respective armatures draw the walking beams 11-8l to the central position upon which the solenoids will become deenergized by breaking the holding circuit previously established at heads 64-68 inclusive, and the arms will be stopped at their central position opening the switches |09| |3 inclusive leading to the apparatus of Fig. 13, and each intersection signal will be thrown out of action at a caution period, the moving element |29 and |30 of the signal relay being so balanced and weighted that it will return to a central off position. Since no subsequent stop light is displayed at each intersection, trafc will proceed without control.

As traic increases or decreases in volume in passing along a given street, due to turns into or out of a given lane, causing a wide variation in the proportions of through and cross traiilc at various intersections, and at the same intersection at different hours, provision is made in this system for adjusting the length of the trains at each intersection in accordance with the traffic demands at that particular intersection. This is accomplished by connecting the signal relay at that intersection to the circuit controlled by the circuit closer having the desired proportions of signal display in the time cycle.

The operation will then be that as a particular train passes continuously along a street, through areas of different proportional trailic densities, as between the through and cross directions, it will be lengthened or shortened in accordance with the varied demands by coming under the control of signals whose control relays are connected to the proper circuit to meet the local requirements, in all cases without interfering with the continuous movement of any train.

To change the proportion of time given to go and stop signals at the station represented in Fig. 13, the plug |23 may be shifted to the socket 220 thus providing a path for current from arm |60 through wire 22|, contact |62, wire 222, whereby to provide a go time of 60% instead of a former 75% and a stop time correspondingly changed. If the plug |23 be placed in the socket 223, a path for current will be provided from arm |64 through wire 224, contact |65, wire 225, thus providing a proportion of go to stop of I It is an important feature of the invention that only a minimum number of wires need be carried through the cable to the intersections successively to operate the system. Fig. 1 shows a proportion of east-west go of 75% and a north-south go of 25%. If exactly the opposite proportion were required, Fig. 1 would nee-d to be inverted. shown at 21 for north-south go would then occur in the position of interval 20 for east-West go, and vice versa.

Since all control wires, both A and B phases of all proportions are conducted to all stations, and a station is made A or B by the relation of its signal positions in the cycle, any station may be made A or B at will.

All the A stations are displaying the midpoint of their go signals in a given direction at the same instant whatever the duration of the signal period may be at any station and all of the B stations are displaying the mid-point of their go signals for the cross direction at the same instant.

By the provision of reversing switches at the A time interval of the value of thatV intersections, as shown in Fig. 13, the circuit closers 32 and 33 are enabled to serve instead of additional circuit closers for the reversal of time interval proportions at intersections and the two wires which are shown leading from each of these circuit closers are enabled also to serve the purpose of the additional two wires which would have to be led through the cable from each of the additional circuit closers, and the control solenoids -94 inclusive at the central station are also halved in number. Moreover, the reversing switches referred to enable the stop and go periods 4controlled by the 50%-50% circuit closer 34 at the central station to be reversed, giving the equivalent of the opposite phase value, thus resulting in a clearly reduced number of wires and control apparatus necessary to produce the re sults procured by the present invention. These reversing switches, shown as |4| and |48 in Fig. 13, actually reverse the signal direction and are mechanically interlocked with the control plugs making connections so that the arms |58, l5! formerly controlling B signals now control A signals, and vice versa, for arms l i6, |60 so as to prevent any error in the operation. They give the opposite time proportions from those previously described as supplied by the circuit closers 32 and 33 for a given direction of traffic movement.

The means for interlocking referred to comprise the sliding plate 226 diagrammatically indicated in Fig. 13 carrying an arm indicated by dotted lines at 221' which arm by movement of plate 229 downward reverses the reversing switches shown in such gure, after which the plug |23 may be placed in either of sockets 221 or 223, the holes 229, 233 in the sliding plate being brought into registry with the sockets 221, 223. When the plug |23 is placed in the socket 221, a path for current will be provided from arm |3| through wire 23|, contact |63, wire 232, socket 221, for 40% east-west go time. If the plug |23 be placed in socket 223, a path for current will be provided from arm |58 through wire 233, contact |59, wire 234, tothe last named r socket 228 for 25% east-west go time, thus enabling the operation of signals in Fig. 13 to be so controlled as to use any proportion of go time provided for at the central station along either street at which the station is located.

The showing of Fig. 13 has been described as an A station, the opposite or B stations being similar to the showing in Fig. 13, except in the reversed relation between the reversing switches |4| and |48 and the position of the sliding plate 226, shown directly connected to the switches by bar 221 (shown in broken lines), and, considered as app-lying to east-west traii'ic at a Bl signal, the sockets will give the reverse proportion of go time, viz.: |22, 25%; 223, 40%; 223, 50%; 221, 60%; and 228, 75%.

Obviously other time proportions may be provided throughout the system by merely changing the rotating member of the circuit closers at the control station for ones of the desired proporf tions; also a system may embrace a greater or less number of time proportions than are shown inthe illustrated form.

If it be desired to take over the control of signais at the station in Fig. 13 manually by a traic officer at the intersection, the same may be accomp-lished by merely manipulating the arm |29 as by means of handle 235, thus overcoming the successive energization of solenoids |25, |26. When the signal system is placed out of operation by pressure of the stop circuit closer |65 at the central station, the weight of the handle may operate to bring the walking beam |29 to a central position out of contact with the control contacts coacting with arm |39.

By reference to the diagram, Fig. 13, it will be obvious that the above mentioned control of signal display by hand may be effected whether the central station timers are in operation or not, as may also the signal blocking operations described in the succeeding'paragraph, since the power lines 31 and 41 are to be kept alive at all times. Another point to be noted is that the signals displayed by any xed position of the hand operation may be used continuously whenever desirable, whether or not the central office timers are in operation. Any of the signal combinations obtainable by automatic operation may be obtained by manual operation.

If it be desired to block oiT a street or area, the stop lights at stations entering upon said street or area may be placed into operation by manual closure of switches |46 or 2|3 with the contacts 236 and 231 respectively. A circuit will. thus be provided from wire 41 through wires 238, 239, contact 236, switch arm |43, wire |45, northsouth stop" lamps |44, to wire 31, which lamps will be continuously operated or from wire 41, wire 238, wire 239, contact 231, switch arm 2I3, wire 2|2, through east-west stop lights 51, which will also be continuously displayed until the switch arm |46 or 2|3 is restored to the position shown in Fig. 13. Such movement of manual switches will also break the circuit through wires |48 and |44 controlling the gof lights at the station to prevent their display by the continued action of walking beam |29 which is not interfered with. It is obvious that the operation of both switch arms |43 and 2|3 will provide the equivalent of a re stop at the intersection in question.' For purposes of blocking off such intersection in the case of a parade the appropriate arm |43` or 2 I3 may alone be operated to display either east-west stop or northsouth stop leaving the signals of the cross direction in operation under control of walking beam |29 so that traflic along one street will not be interfered with.

Thereis shown an audible signal as a bell at 24|) which is normally sounded at each cautionI period by a circuit from wire 31 to the bell, wire 24|, switch arm 242, wire |34, of the caution circuit. If it is not desired to sound the bell, the switch 242 may be manually opened to cut the same out of action.

It will be observed that the sequential starting, stopping, and fire signal control is accomplished in such manner, by means of the interlocking and holding contacts, that any one of these operations, once started by momentary closure of the buttons 36, |65', or |81, will be completed before another can be started. Also any of these operations maybe put into effect regardless of which other operation has preceded it.

In the case of nre, when it is desired to stop trafc through the entire area under the control of a particular central control apparatus, the circuit closer |81 is operated, providing a path for current from wire 31 through wire 38, circuit closer |81, wire |88, contacts 52, wire |89, contacts |90, wire |9|, solenoid |92, wire |93, to wire 41, thus energizing the solenoid |32 and closing a holding circuit from wire 41 through the solenoid |92, contacts |94, wire to bus wire |96, each of .contacts |91-to 20| inclusive,

heads 64 to 68 inclusive, wires 69 to 13 inclusive, bus Wire 14 to wire 31, and the energization of solenoid |92 will close contacts 202 and 203, thus providing a path for current for solenoids 88, 88, 90, 92, and 94, that through 86 being as follows: wire 41, contacts 202, Wire |85, wire |84, solenoid 86, wire 294, the upper brush 84, caution period segment upon drum 82, band 98, brush 91, Wire 96, wire 15, contact 203 to wire 31. A like circuit will exist through each of the other solenoids 88, 90, 92, and 94 by means of wire |84, wires 205, 206, 201, and 208, through the corresponding brushes 84, the segments on drum 82, band 98, brush 91, Wire 96, Wire 15, contact 203, to Wire 31.

The result of thus pressing the re signal control circuit closer |81 will be that the right hand end of walking beams 11 to 8| inclusive will be depressed at the next succeeding corresponding caution period, thus causing switches |89, H0, H2, and ||3 each to close with the lower contact to complete the circuit, which for 2d and D Street signals is as follows: the

wire 41 at the right hand end of transformer ||9, switch |09, wire ||5, socket |22, plug |23, wire |24, solenoids |25, |26 to wires 41 and 31 respectively at the control station. By this connection, the entire potential between Wires 31 and 41 will be placed upon solenoid |25, Fig. 13, causing the walking beam |29 to be thrown completely downward thus bringing the arm |30 upon contacts 209, 2|0, and 2| I, thus closing a circuit through both north-south and east-West stop signals at this station, and at all other stations controlled by the same polyphase circuit wire, and also through an audible nre signal at the same stations. Since the solenoids 88, 88, 90, 92, and 94 will be energized only at the beginning of a caution period, (the action of commutator 82), the fire signals at the separate intersections will not all be initiated simultaneously but only at the beginning of a caution period for each intersection.

Figs. 1 to 9 illustrate a system operating with l.' a single time proportion cycle, in which, as will be evident in Fig. 1, there are four caution instants in the cycle, any of which is a possible instant for the display of a fire signal at the stations in its phase. The initiation of a fire signal display in the system by the closure of circuit closer |81 between the instants indicated by the dot and dash lines 2 and 3 in Fig. 1 will cause a display of the ire signals of the stations under the control of phase B at the arrival of instant 3, but there will be no change in the signals under control of phase A until the arrival of instant 1. This delay is due to the action of the segments of the commutator drum 82.

The display of all stop signals at an intersection, combined with the sounding of the siren instead of the bell, coming at a normal caution instant, necessarily just preceding a go signal, will automatically stop the leading cars of each approaching train before they enter the intersection. Any signals operating with other time proportions which would arrive later at their caution instant, would, by displaying the all red "stcp signals at that later caution instant, close their crossing after the scheduled passing of the rear car in the longest trains being accommodated.

Trains moving in a section where a major portion of the cycle is devoted to one direction of .i travel, making their length greater than one block, as the east-west trains 23 and 25 of Figs. 5 to 9, inclusive, will be conned within one block in the following manner: Trains operating on a 75% portion of the cycle will be less, by the caution distance, than one and a half blocks long, requiring a shortening of the trains by less than one third of their length, and there will be spaces between vehicles following each other in the train equal to the vehicle length or more, or a solid density of not more than 50%.

For illustration, if the rst display of the re stop occurs in front of the leading cars of trains 23 and 25 approaching the B signals at the instant of Fig. 5, a packing together of all cars in the trains as they come to a stop will result, easily reducing the length of the stopped trafc trains during the time elapsed between the instants of Fig. 5 and Fig. 7 so as to clear the intersections of lst and 3d Streets with D" Street behind trains 23 and 25. During this interval, the rear cars of each long train 23 and 25 will have cleared the intersections under control of the A signals, and the small trains, as 24, 24', willhave moved from the intersections under the control of the B signals and will be stopped at the A signal intersections at their arrival, which would be at the instant of display of the fire stop signals at the A stations.

With a plurality of dual interlaced systems, trafiic will not be stopped simultaneously in all blocks but each train will reach the next intersection when the caution signal would have been displayed, and the following signal will in each case be a stop signal. The traffic will pack into alternatey blocks and will provide a free zigzag course for the run of fire apparatus along each street alternately upon the left and upon the right, all intersections being clear.

The path for current at a fire stop through north-south stop signals |44 is as follows: lamps |44, wire |45, switch |46, Wire |41, reversing switch |48, wire |49, contact 209, arm |30, to wire 41.

Through east-west stop signals, the circuit is as follows: lamps |51, wire 2|2, switch 2|3, wire 2|4, reversing switch |48, wire 2|5, contact 2|0, arm |30 to Wire 41. The circuit through the siren 2|6 would be from wire 31 to wire 2|1, normally closed switch 2 |8, wire 2|9, contact 2| arm |30, to wire 41.

In cases where there is occasion for a run of re apparatus throughout a denite route, as where after a iire alarm has been responded to by the fire department it is found desirable for apparatus from one station to run to another station for strategic disposition of reserve re apparatus, provision is made in the system of the invention for a iire control of signals to group the trains in alternate blocks on opposite sides of the streets, leaving a clear zig-zag course for the re apparatus throughout said deiinite route. Apparatus for this purpose is illustrated in Fig. 14.

As shown in Fig. 14, a control Wire leading from wire 31 at the nearest street intersection is connected through to a hand switch 243 located at the re station and a control wire 244 with the apparatus controlling each intersection, successively through the route selected. When the switch 243 is closed, a path for current is provided from wire 31, switch 243, wire 244, solenoid 245 at each street intersection on the route, Wire 248, arm 241, wire 248, extra contact |3| in caution position, which upon the rst movement of arm |30.` at each intersection on the route will connect with wire 41, thus energizing solenoid 245 which attracting its core 249 will close the hold-up circuit for solenoid 245 through arm 241, arm 248', arm 249 via contacts 259, now closed, to wire 41. At the same time a path for current will be provided from wire 31 through solenoid |25, wire |24, arm 248', contacts 259, arm 249', to line 41.

In this event solenoid |26 will be short circuited since the same will be connected at its top directly to wire 41 and at its bottom through wire |24, arm 248', contacts 25D, arm 249', to the same wire, thus putting full potential on solenoid for display of fire signals, wherein the arm |39 contacts with contacts 209-2H3-2Ii, which, as already explained is the fire signal position. The control path through plug |22 and wire |24 having been broken at contacts 25|, normal control of signals along the selected route is interfered with until the switch 243 is again opened allowing the spring 248 to restore the parts to the position shown in Fig. 14. Springs 252 and 253 serve to hold the arms 241 and 249 respectively in contact with stops when arm 248 is in released position.

While the wires 31 and 41 have been shown for convenience of illustration as carried through the cable to all intersections successively it Will be obvious that in cases where the signal lamps are illuminated from the city light supply the connections to the wires 31 and 41 at each street intersection may be made directly to said city light supply, care being exercised to make the connections thereinto at each intersection of proper phase, potential and polarity. This allows the lamp load to be carried from local supply, relieving feed cables and reducing the number of wires required.

In Fig. 15 is shown the diagram of circuits for control of an intersection of three streets, such for instance as shown at the centre of Fig. 11 where a diagonal street called X Avenue on said figure intersects with both B Street and 2d Street. At such an intersection there are obviously required go, stop, and caution lamps facing each direction upon each street. Ihe lower right corner of Fig. 15 indicates an apparatus such as shown in Fig. 13 and the preferred mode of operating the signals at such an intersection is to give a mino-r proportion of time to one street, as B Street, Fig. 11, and to divide the major por tion of time which upon the other streets in the vicinity is given to east-west traffic, as 2d Street, into two parts, one allowing movement along 2d Street and the other allowing movement along X Avenue.

As indicated by the legends opposite the lamps, the upper three pairs of lamps are caution lamps, the central three pairs are stop lamps and the bottom three pairs are go lamps, the top pair of each of the three sets being dedicated to B Street, the central pair of each set to 2d Street and the bottom pair of each set to X Avenue.

Provision is shown in Fig. 15 for a manual control `of the signals at such an intersection which for convenience will iirst be described. Said manual control comprises a circuit closer diagrammatically shown as an arm254 revoluble about an axis 255 and in its off position shown in the gure closing circuits to the automatic control shown in the upper right corner of said figure. If the arm be swung to the right of its position, a path will be provided for a current from wire 41 to contacts 256, 251, 258, which will close circuits via wires 259, 260, 26|, to go signals on B Street, and to stop signals on X Avenue and 2d Street respectively, the current passing from said lamps directly to wire 31 connected to said lamps in parallel. Movement oi the arm into contact with contacts 262, 263, 264, and 265 will close circuits through wires 256, 265, 261, and 263, to bell 246, stop lamp on X Avenue, caution on B Street, and caution on 2d Street. Movement of the arm into contact with contacts 269, 210, 21| will cause the circuits through wires 212 to stop on B Street, through wire 260 to stop on X Avenue and through wire 213 to go on 2d Street.

Movement oi the arm into contact with contacts 214, 215, 216, and 211 will cause the circuit through wire 269, to the bell 240, through wire 212, to stop on B Street, through wire 268 to caution on 2d Street, through 218 to caution on X Avenue.

The arm 254 when moved into contact with contacts 219, 220, and 28| will close the circuit through wire 212 to stop on B Street, through wire 25| to stop on 2d Street and through Wire 231 to go on X Avenue. When the arm 254 is moved to contact with contacts 262, 283, 294, and 225, a circuit will be closed to the bell 249 through wire 266, through wire 26|, to stop on 2d Street, through wire 216 to caution on X Avenue and through 261 to caution on B Street.

It will be noted that in the operation of the hand control as described above, or in the reverse rotation ci arm 254, as well as in the automatic operation described in the following paragraphs, there is a caution signal displayed on a signal face only just preceding a change of signal display on that face, and no caution signal is displayed on the face which is not to be changed at the next signal change instant.

In automatic operation, the function of the contacts coacting with arm 254 will be performed by the solenoiols shown in the upper right corner of the iigure, except the position for go on B Street which is controlled directly by walking beam |29.

For control of the solenoids a motor 286 is provided operating a cam wheel 281 and a commutator drum 288. To close a circuit through the motor when the system is to be placed into operation, there is shown a Wire 289 leading from the upper portion of Fig. 12 where it mayv be placed into connection with wire 31 by means oi a manually operated switch 299. Said Wire leads through the cable to the signal station to solenoid 29| and from the solenoid through wire 292 to switch arm 254 which is connected to wire 41, thus causing the solenoid to close contacts 293 and 294 whereby to close a holdup circuit from wire 41, through contact 294, wire 295, contact 296, arm 291 when actuated, motor 286 to Wire 21. Wire 41 is connected through arm 254, wire 292, and contact 293 when closed, to the wire numbered 41 which supplies energy to the arms in the upper portion of the ligure, as, e. g., 329.

Assuming that the lower right corner of Fig. 15 illustrates a B signal and with the switch arm 254 locked in the position shown, a circuit will be closed from wire |24 carrying the plug |23 to arm 293 held depressed by the end of arm 254, contacts 299, wire 30|) to solenoids |25 and |26, which in turn are connected in the manner shown in Fig. 13.

Upon the first movement to the left of arm |33 the go signal on B Street will be actuated from wire 41, through arm |39, contact |54, reversing switch MI, wire |133, through the lamps to wire 31, and a parallel path will be closed from wire |013 through wire 33|, solenoid 332, wire 303 to wire 31, thus energizing the solenoid and pulling down arm 3M and closing a path from wire d1, arm |33, contact |55, wire 255, reversing switch |453, wire 2M, wire 305, contacts 306, arm 336i, wire 331, wire 333, to stop signals on X Avenue, also on the path already traced from contact |55 to wire 2id and to stop lamp on 2d Street. When the arm |30 leaves contacts |53, |55, the arm 3534 will again be raised closing a path from wire G1 through wire 333, the right hand end of arm 304, contacts 3HE, wire 3| l, brush 3|2, wire 343, contacts 3M, arm 291, motor 233, wire 31, which will start the motor and will also close a path through hold-up solenoid 3|5 in shunt with the motor 236 which will draw over arm 231 in contact with contact 233 against the resistance of spring 3| 3 closing a circuit from wire Il?, contact 294, wire 235, contact 233, and arm 231, to solenoid 3|5 and to wire 31.

Revolution of the motor will first bring brush 3|1 into contact with segment 3|8 on commutator 288 thus energizing solenoid 3| 9 to draw down arm 320, thus closing the circuit from wire 41', arm 320, contacts 32|, to caution lamps on B Street through wire 322, contacts 323, through wire 323, to caution on 2d Street, contacts 325, wires 32S, 321, to bell 233 and contacts 328, wires 323, 333 to stop on X Avenue.

Continued revolution of commutator 283 closing segment 33| with brush 332 provides a path for current from wire 31', wire 399,' arm 334, contact 3i3, wire 3| l, brush 3|2 to the commutator and wire 333 to solenoid 334 which draws down arm 335 closing the contacts associated therewith, at the same time solenoid 3I9 being de-energized to release the circuits controlled thereby. The contacts 336 closed by arm 335 will provide a path for current from wire 41', wire 331, the contacts, wire 333, to go lamp on 2d Street, also closing the circuit through wire 31, wire 331, arm 335, contact 333, wire 343, wire 333, to stop on X Avenue and over the rst part of the same path through contacts 34|, wire 332, wire 333, to stop on B Street. Further rotation of commutaor 282 for bringing segment 3d@- into contact with brush 345 will energize solenoid 346 attracting its arm simultaneously with the breaking of the circuit through 334, thus placing caution signals on 2d Street, on X Avenue, closing a circuit through bell 243 and placing a stop signal on B Street by readily traced circuits.

Further rotation of the commutator bringing segment 341 into contact with brush 343 energizes solenoid 349 and de-energizes solenoid 346, thus displaying a go signal on X Avenue, a stop signal on 2d Street and a stop signal on B Street. Contact with segment 35i! with brush 35| energizes solenoid 352 thus ringing bell 233 and displaying caution signals on B Street, X Avenue, and a stop signal on 2d Street.

The motor 236 is adjusted to revolve the commutator 288 to the last named caution period at approximately the instant when motor '35 at the central control station has brought the arm of the circuit closer thereat, which controls the operation of arm |29 to display a go signal again on B Street, the display of which go signal by closing the parallel path through solenoid 302 will break the circuit from wire 41 to brush 3i2. It is assumed that the go signal onI B Street referred to is given a minor proportion of the moving time and that the major portion has been divided between X Avenue and 2d Street by the automatic control through sole noids 3|9, 334, 346, 349, and 352.

Breaking of the contact 3H! however will not stop motor 285 since the current to the motor is still supplied by virtue of its hold--up magnet 3| 5, the motor 28S will therefore continue to revolve for a slight additional period of time until cam 353 catches hook 353 further stretching spring 3|6 and until the cam slips oi the hook by hammer action of lug 355 against the end of arm 291 breaking the holdup contact 296 thus stopping the motor.

By this arrangement the go signals on B Street at the intersection in question will be utilized to synchronize the remaining signals at said intersection with the other A and B signal stations in the system.

It will be noted that it is proposed to operate this system of traiic control on a Xed time cycle, which requires traiiic to move at speeds approXi mately in proportion to the block lengths to move continuously. It is not proposed to vary the length of the time cycle, therefore the traflic speed for any given block will remain constant and drivers will become accustomed to this speed and to the necessary variations for different blocks.

As longer blocks required higher speeds and a block of twice the standard length requires twice the standard speed, it is proposed to place consequent signals at the center of such long blocks which will take their regular place in alternating phase sequence, for the purpose of keeping the traic grouped in trains and dividing the traveling distance between signals to give reasonable traffic speeds. Such a signal is indicated at 356, Fig. 10. In the position there shown the signal is indicated as an A signal placed between two B signals and at a point in a long block where an A signal would occur if a short end street were cut through. The consequent signals require only go and caution lights and may be assumed to be controlled by mechanism similar to that shown in Fig. 13, the stop contacts and Wiring being connected to amber lights instead of to red lights and the amber light control contacts being omitted. With this arrangement the green lights upon the consequent signal would bear an indication of the correct speed for driving to arrive at the proper moment at the next street intersection and the amber lights will be displayed when a stop light would otherwise be displayed if the short length street were cut through. Traffic in such a block upon observing a caution light as they approach the caution signal will thus be informed that they are in advance or" their schedule and must slow down if they do not de sire to arrive at the next intersection too early for continuous movement.

Consequent signals are also indicated at 356 on X Avenue in Fig. 11 upon which avenue the intersection lights are indicated as B signals and the consequent signals as A signals, which will therefore synchronize the movement of traffic with the A signals along X Avenue.

With this system, using a xed time cycle and various traffic speeds for various length blocks,

. place inthe phase alternation system.

traffic should be advised by signs, preferably on the signals, at what speed to travel in the succeeding block as an essential part of the system.

The following method is suggested for laying out such a system in any given city merely to illustrate the principles involved.

Establish a standard block for the area to be controlled giving due consideration to the actual short and long blocks and their importance in the area, and establish a time cycle to give a reasonable trafc speed in the standard block. This standard block need not be the exact length of any actual block, but it would probably be near the average length. From this standard time cycle and Standard block length, calculate the proper driving speeds for each actual block and post, on each signal face, the proper speed for the succeeding block for traiiic under control of that face.

Driving speeds should be increased from the standard to accommodate increase length up to one and one-third times the standard length, and decreased from the standard speed to accommodate decrease in block length down to two-thirds of the standard. 1n blocks of more than one and one-third times the standard length, a consequent signal should be inserted midway of the long block and take its When blocks are less than two-thirds of the standard length, one street, as 359 in Fig. l0, should be blanked off with stop, no-left-turn and nocrossing signals and not considered in the aiternating signal system, calculating and posting the speed for the composite block created by the suppression of the intersection.

To show that the general proportions of this system of speed allotments remain within reason, take for illustration a standard block length of three rhundred feet, with the minimum block -length two hundred feet and the maximum block length four hundred feet; then if the standard `block speed is twelve miles per hour, the maximum block will have a speed of sixteen miles and the minimum block will have a speed .of eight miles per hour. rI'his illustration takes in the extremes in both directions and the longest block used is twice the length of the shortest block. Any block that was in excess of four hundred feet and split by a consequent signal would have a speed of eight or more miles per hour, -while any two blocks of less than two hundred feet, would have if combined, a speed of less than sixteen miles per hour. Blocks in excess of six hundred feet may have more than one consequent 5 nal blocks in Fig. 10 are about one and one-half this standard length and would require a trailic speed of one and one-half times the standard speed. Assuming the standard speed to be -ten miles per hour, the faces of signals leading north, south, east, and west in Fig. ll and those leading north and south in Fig. 10, would bear ya legend indicating ten miles per hour, while the signals facing eastor west in Fig. would indicate nf- 'teen miles per hour. The -signals along X Ave- 75 nue, Fig. '11, would bear indications of seven in blockmiles per hour, the hypotenuse ratio of '1.41 times the length of 'the standard block being divided in two by the phantom signals between intersections.

Obviously, successive blocks in the same street which are of different dimensions call for different speed signsas for illustration, the east and west streets in Figs. 10 and 11 taken as a single continuous plan.

Consequent signals have as their function to adjust the speed of traino at points other than rthe regular intersections of a network, as in unusually long blocks, or between Ithe intersections on a diagonal street, or along a driveway through a park, or at approximately a block away from the rst regular intersection signal of a controlled area, in which cases the consequent signals take their regular places in the alternating A and B phases to harmonize the tralic with the signals at the junction points with the regularly controlled network.

The cables bearing the control wires have been described as running successively through the intersections of the system. For connection of the cables there are indicated at 351 and 358 in Fig. 13 junction boards for connection to the cables it being obvious that a trunk line can be carried out a through street from the control station and by means oi junction boards such as shown the branches to other intersections upon either side of the trunk line may be connected in.

1n addition to this arrangement it is proposed to carry a ring cable carrying one each of the wires in the main control cable to Lan outlying point and to conduct this vcable around the outskirts of the area connecting the same into the intersections therealong. By provision of such a ring cable two paths for control will exist to all of the intersections within the ring and should a cable be broken leading to a certain area as by demolition of a control box at a single intersection the remaining signals may receive circuit via the ring cable and therefore service will not be interrupted except at the damaged intersection. It is not considered necessary to show the connection for such a ring cable as it appears obvious.

Obviously more than one connection may be made to one cable or a plurality of cables may be provided.

While the system has been described utilizing an auto transformer for varying the potential applied to the conductors leading to the sig-nal stations, Vit will be understood that direct current can be used as by floating a storage battery across the line at the control station and tapping ofi the desired differences of potential thereon.

It is also contemplated to use the circuits and apparatus illustrated in Fig. 15 at intersections of two streets only, using one or more of the additional periods thus secured for left turns or other special purposes.

The operation of the system will be clear from the above description, Minor changes may be made in the circuits utilized, in the character of the apparatus diagrammatically illustrated, or in the steps of the methods of the invention within the scope of the appended claims without departing from the spirit of the invention.

I claim:

1. A method of controlling traffic divided into separated trains moving on a controlledschedule, for providing'for runs of re apparatus Which comprises displaying a fire stop signal at the caution period in advance of the scheduled arrival of the front end of each train at the next street intersection whereby to coni-lne the whole.

of each train within a single block with the opposite side of the street therein normally vacant for use of the fire apparatus.

2. The system for controlling trac upon a system of intersecting streets which comprises a central station, conductors maintaining constant line potentials throughout the system a plurality of circuit closers at said station operating in a common time cycle, a plurality of signal stations each equipped with go and stop signals, two pairs of conductors connecting said circuit closers with each of said signal stations successively, means controlled by said circuit closers for applying diierent potentials intermediate to said line potentials to said conductors for different periods of time, as 60% and 40% of each time cycle by one circuit closer and as 75% and 25% of each time cycle by another thereof, the central points of equal potentials at adjacent stations being separated by substantially 180 of the time cycle of the circuit closer, means at the signal stations to display go and stop signals in accordance with the potential upon a connected conductor and means at each signal station to make connection of a go and stop signal display means to a selected one of said conductors.

3. A traffic control system comprising, in combination, means at a central station for controlling in proper phase position to give progressive traflic a display of go and stop signals on one set of streets and for controlling a display of stop and go signals on a second set of streets intersecting said iii-st named streets, consequent signals placed in abnormally long blocks in said streets displaying only go and caution signals and means at said station for controlling said consequent signals to display go signals in proper phase posititon with other signals on the streets `including said long blocks and to display caution signals for the rest of the time to give progressive traic.

4. A traiic control system comprising, in combination, a central control station, a signal station having a plurality of go and stop signals for display in a plurality of directions, means at the central station for controlling the routine traffic display of each of said signals, means at the signal station for continuously displaying selected stop signals in given directions thereat and inhibiting the central station control of -go signals for the same directions leaving the remainder of the signals at the said signal station under uninterrupted control of the central station.

5.A trac control system comprising, in combination, a central control station, a plurality of signal stations each having a plurality of go and stop signals for display in a plurality of directions, means at the central station for controlling the routine traffic display of said signals, means at the signal stations for continuously displaying selected stop signals for given directions and inhibiting the display of corresponding go signals for the same direction leaving the remainder of the go and stop signals at that station and throughout the system under uninterrupted control of the central station.

6. A traic control system comprising, in combination, a central control station, a plurality of intersection signal stations having go and stop signals, means at the central station to control display of said signals to cause traffic to progress in separated trains continuously past the said signal stations, and means at the central station to cause continued display of all stop signals as during response to a re alar initiating said stop signals at the intersections at such instant in the time cycle of signals and in such sequence as to stop the traiiic trains and hold the traffic in alternate blocks on opposite sides of the streets, leaving a clear zig-Zag course through the street system for use by the re apparatus.

7. A traffic control system comprising, in combination, a central station, a plurality of signal stations, go, stop, and caution signals at said signal stations, means at the central station for controlling display of said signals and means at the central station to cause continued display of the stop signals initiating such continued display at the next occurring caution period at each signal station.

8. A traffic control system for a network I intersecting streets comprising a plurality or electrically controlled stations for displaying go and stop traic signals in a fixed time cycle, the stations consisting o-f A stations and B stations alternately arranged along both through and cross streets, the A stations and the B stations forming two systems, each system under a common control, means for causing the A stations to dier from the B stations by a difference in phase of 180 in the mid-point of the time of display of corresponding signals for a given direction in said xed time cycle which is the same for both A and B stations, and means causing the period of simultaneous display of signals to be of unequal duration in the two phases.

9. A traic control system comprising conductors maintaining constant line potentials throughout the system, two control conductors, means for imposing in a recurrent cycle, upon said two control conductors, two principal, different, alternating control potentials each intermediate to said line potentials, each substantially constant during two different, recurrent major periods, alternating in length and denite in duration, the mid points of both major periods being equally spaced from each other in the cycle, said two conductors receiving equal control potentials alternately, the mid points of the two principal, diiierent control potentials being synchronous in the two conductors, a plurality of stations at intersections of two streets, each having means actuated by said control potentials for displaying two diierent major signals, go and stop, for control of traic moving in opposite directions in each street, go signals alternating with stop signals at each station on each street and at successive stations along each street in through and cross directions, and means at each station for connecting either conductor at will to means for displaying either the go or the stop signal upon either street, for actuation during either period.

10. A traiiic control system comprising two groups of control stations, A and B, for control of go and stop signal displays, the A stations being located at alternate signal locations in a network of streets and the B stations being located at intermediate signal locations in the network, a plurality of control means selectively available at control stations and operating in a common time cycle and each capable of causing a control station to display "go signals for a different definite proportion of the time cycle for a given direction, and means for malclng operativel the control means causing signal display for the proportion of the common time cycle desired at that particular signal location, the system including means for maintaining a phase angle of substantially 180o of the common time cycle between the mid-time instant of any go signal display for a given direction at any A station and the mid-time instant of any go signal display for the same direction at any B station.

11. In a traific control system as in claim 10, in which certain control means cause the display of "go and stop signals for unequal proportions o-f the time cycle, means for converting the control intended for a go signal display for a given direction at an A station for a greater proportion of the time cycle into a control of a go signal display for the same direction at a B station for the smaller proportion of the time cycle, and vice versa.

12. A trailic control system comprising, in combination, conductors maintaining constant line potential throughout the system, a central station, a plurality of signal stations at intersections, conductors extending from said central station to said signal stations, means at said central station to apply different definite potentials intermediate to said line potentials for different denite periods of time upon each of said conductors in a regular sequence, certain of said conductors having the same sequence of denite intermediate potentials applied for the same periods as certain other conductors, in pairs, the central point of periods ci like potential 'being spaced substantially 180 of cycle of said central station, as between conductors of each pair, the separate pairs being supplied with like potentials for periods forming d iiTerent proportions of the time cycle, go and stop signals at each of said signal stations, a circuit closer at each of said signal stations to control said signals in accordance with the potential applied to one of said conductors intermediate said line potentials, means at each signal station for connecting the circuit closer with a conductor of different pairs, selectively, whereby signals for a given direction of traflic movement may be displayed for different lengths of time at adjacent intersections, while maintaining the essential alternating phase angle of the signals at adjacent intersections to produce continuous progression of traic.

13. A traffic control system comprising, in coinbination, conductors maintaining constant line potential throughout the system, a central station, a plurality of signal stations at street intersections, two control conductors extending from said central station to said signal stations successively, means at said central station to apply diierent definite potentials intermediate to said line potentials for diierent definite periods of time upon e-ach of said conductors in a regular sequence in a iixed time cycle, the central point of periods of like potential in the two conductors being spaced substantially 180 of the time cycle of said central station, go and stop signals at each of said signal stations, a circuit closer at each of said signal stations to control said signals in accordance with the potential applied to one of said conductors, said signal stations operating to display the go signal during the longer period of time, and the stop signal during the shorter period of time of the cycle for one street at an intersection, the two conductors being connected alternately to successive signal stations, and the displayed signals alternating go and stop at consecutive signal stations.

f 14. A traffic system comprising in combination, two interlaced systems oi signal control, the signals of each of the two systems being arranged on alternate intersections of any given street of e. plurality of intersecting streets, a central station having means to cause the simultaneous display for each system of go signals for progressive control of trafiic upon streets running in' one direction, as east-west, for a major portion of a time cycle, alternated at adjacent intersections with the display of stop signals upon said streets for a minor portion of the time cycle, and means at said station to cause a display of go signals for progressive control of trac upon the streets running in the other direction, as north-south, for a minor portion of the time cycle, alternated at adjacent intersections With a display of stop signals for the same street for a major portion of the time cycle.

15. A system as recited in claim 14, in which the half-way point of the period of time of display of the go and stop signals of each system is substantially synchronized with the halfway point of the period of display of the stop and go signals respectively, of the other system.

16. A trame control system for a system of intersecting streets cut by a diagonal street having a common intersection with two other intersecting streets, comprising, in combination, means at a central station for controlling the display of go and stop signals timed for continuous movement in both directions along said intersecting streets, and means for controlling a display of go signals upon said diagonal street at the said common intersection for a time interval subtracted from the go time along one only of said intersecting streets at said common intersection, alternated with a stop signal while a go signal is displayed upon either of said intersecting streets. l

17. A traffic control means comprising a plurality of signal stations forming a system having two electrical controls, one controlling the signals at alternate stations and the other controlling the signals at intermediate stations,

means for operating the controls to display go and stop signals through denite variable periods, .in uniform time cycles, the central point of a period of display of a go or stop signal for a given direction by one control being spaced substantially 180 of the time cycle from the central point of the period of display of the corresponding signal for the same direction by the other control.

18. A traic control system comprising in combination, signal stations at intersections of streets, means for displaying go and stop signals at said signal stations for continuous movement of traffic in trains in said streets, the said signals operating in a denite time cycle, and "consequen signals at points other than trafc crossing lanes displaying only go and caution signals having means for displaying go and caution signals, the go signals being oper-ated in accord with the time cycle and spaced from other signals to harmonize the movement of traffic toward the intersections under control to agree with the progression of traic trains and the caution signals being displayed during the period in which the go signals are not operated.

19. A traic control system comprising a plurality of signal stations, a central station having means controlling said signal stations for progressive traflic in a common traiic signal cycle, each signal station having means displaying routine trafiic signals, the length of the time cycle and the duration of each signal being controlled from said means at the central station, the central station control means having a plurality of control means giving signal periods forming diierent divisions of the common time cycle and said control means maintaining synchronism of the mid-point of the time of display of like signals, each signal station having signal display means cooperating with any selected one of the said plurality of control means, a plurality of control means being available for selection at each station, whereby a desired division of the time cycle may be selected from those available to control the proportions of the time cycle allotted to signals at that station.

20. A traffic control system for a system of intersecting streets cut by a diagonal street having a common intersection With two other intersecting streets, comprising a central station having means for controlling the display of go and stop'signals for continuous trac movement in both directions at two-street intersections in the system, and control means at said common intersection responsive to central station control for the display of go and stop signals for one street only at the said common intersection, and having means automatically controlling the display of go and stop signals in a regular sequence for the other streets at the said common intersection during the period of display of the stop signal on the street not under the control of the automatic means at the intersection.

21. A traflic control system for continuous progression in all directions of travel, comprising a plurality of signal stations, a plurality of pairs of conductors extending to each station,

means for applying similar electric controls in each conductor through a succession of denite periods in a common time cycle, comprising means for varying the period of similar electric controls in the different pairs of conductors but maintaining their midpoints displaced by degrees in the said common time cycle, and in synchronism, go and stop signals at each station, means at each station responsive to said electric controls in any conductor for displaying said signals for through and cross direction in periods of a routine traiiic cycle in accordancev With the periods of said electric controls in said common time cycle, and means at each station for connecting said signal display means selectively with certain of said conductors whereby the signals may be displayed for either a longer or a shorter go or stop period of a tramo cycle While maintaining progressive traffic.

22. A trailc control system for continuous progression in all directions of travel, comprising a plurality of signal stations, a plurality of pairs of conductors extending to each station, means causing varying electric controls in each conductor through a succession of definite periods in a common time cycle and for causing the periods of a particular electric control in the Wires of a pair to be equal in time While maintaining the midpoints of said equal periods displaced by 180 degrees of the time cycle as between the conductors of each pair, but in synchronism at their midpoint and for diierent periods as between different pairs, means at each station responsive to said electric controls in any conductor for displaying go and stop signals for through and cross traffic in periods of a routine traic cycle in accordance with the periods of said electric controls, and means at each station for connecting said signal display means selectively with certain of said conductors whereby the signals may be displayed for either a longer or a shorter go or stop period of a trac cycle.

JESSE C. BUERKE. 

